Effect of low doses of estradiol on 6-month growth rates and predicted height in patients with Turner syndrome.

We randomly assigned 16 girls with Turner syndrome, age 5 to 15 years, to receive treatment with 100 ng/kg/day ethinyl estradiol or placebo for 6 months, with crossover after a 2-month interim period. We assessed growth by measurement of the 4-week lower leg growth rate and by height velocity. Bone age was determined at the beginning and end of treatment. Growth rate during ethinyl estradiol treatment was approximately 70% greater than during placebo (P less than 0.001), without any bone age advancement relative to that with placebo. The change in predicted height was significantly greater after 6 months treatment with ethinyl estradiol than after treatment with placebo (mean +/- SEM, +0.35 +/- 0.38 cm vs. -0.85 +/- 0.32 cm, P less than 0.03). Breast budding occurred in six patients. We conclude that it may be feasible to begin low-dose estrogen therapy to promote growth at an earlier age than would be conventionally used to induce pubertal development. These data are still relatively short term, however; until long-term data are available, it would be premature to make definitive recommendations regarding the dose and timing of estrogen treatment in Turner syndrome.